1. Field of the Invention
The present invention relates to an inorganic composition, a film and a method of producing the film. More specifically, the invention relates to an inorganic composition that contains an inorganic layered composition within an inorganic matrix to provide excellent gas barrier characteristics even in high humidity, a film made from the inorganic composition, and a method of producing the film.
2. Description of the Related Art
It has conventionally been known that film containing an inorganic layered composition has high barrier characteristics with respect to gases such as oxygen, carbon dioxide and nitrogen oxide, and also to low molecular compounds.
For example, Japanese Patent Application Laid-Open (JP-A) No. 8-282112 discloses a multicolor heat-sensitive recording material that includes an intermediate layer and/or an undercoat layer. When an inorganic layered composition having a high aspect ratio is incorporated into the intermediate layer and/or the undercoat layer, it becomes possible to raise, with a thin film, barrier characteristics with respect to substances without adversely affecting transparency of respective layers.
Moreover, JP-A No. 10-90828 discloses that it is preferable to incorporate a swelling inorganic layered composition into layers of photographic elements (e.g., silver halogenide photosensitive materials) to thereby control interlayer spreading of photographic compounds (e.g., pigments) added to respective layers of the photographic elements and to prevent atmospheric gases from spreading into the photographic element layers.
Synthetic mica is preferably used as swelling inorganic layered compound. Moreover, a hydrophilic colloid, such as gelatin, or a synthetic hydrophilic polymeric substance, such as polyvinyl alcohol, is preferably used as a binder in the layer(s) to which the inorganic layered compound is added.
When a hydrophilic colloid such as gelatin or a synthetic hydrophilic polymeric substance such as polyvinyl alcohol is used as a binder in film or in the layer(s) to which the inorganic layered compound is added, it has high barrier characteristics with respect to gases and low molecular compounds in low humidity (i.e., in a dry environment) and exhibits excellent performance. However, barrier characteristics drop remarkably in high humidity (80% RH or higher), which results in an inability of the inorganic compound to sufficiently function as a layer (film) to control dispersion and the like of substances.
There has thus been a strong demand for an inorganic composition containing an inorganic layered composition whose barrier characteristics with respect to gases and low molecular compounds do not drop even in high humidity (80% RH or higher) and that is capable of controlling substance dispersion, and a film made from the inorganic composition.
Examples of techniques for forming an oxide coating film or film on a base material conventionally include melting, such as glass lining and ceramic coating, solution immersion using liquid phases, and a sol-gel method.
In the sol-gel method, water-containing oxide sol, such as metallic cation and metal alkoxide, is dehydrated to form a gel, and the gel is heated to prepare an inorganic oxide having a fixed shape (e.g., film, particle, fiber etc.). This method is known because synthesis is possible at low temperatures, highly pure products can be prepared thereby, and control of compositions is easy (see Japanese Patent No. 2538527).
However, there have been proposals with respect to film that is prepared by the sol-gel method and is thin, has superior barrier characteristics with respect to gases and substances such as low molecular compounds, and that can function as a heat-sensitive recording material and photosensitive material.